|
|
|
Your donations help keep this valuable resource free and growing. Thank you.
|
AMC 401 Rebuild Path Forward Sanity Check |
Post Reply 
|
Page <12 |
| Author | |
shootist 
AMC Addicted 
Joined: May/24/2012 Location: Triad, NC Status: Offline Points: 1023 |
 Post Options
 Thanks(0)
 Quote Reply
 Posted: Dec/13/2018 at 1:48pm |
|
My vote would be with White70 and DRS, Sleeve 7 as a reliable and cost effective approach.
|
|
|
|
 |
|
|
Trader
AMC Addicted
Joined: May/15/2018 Location: Ontario Status: Offline Points: 6910 |
Post Options
Thanks(0)
Quote Reply
Posted: Dec/13/2018 at 2:21pm |
|
Lowry didn't say #7 needed a sleeve. I stated IF there is core shift, #7 seems to be the usual problem when over boring is required, and a sleeves are viable options.
Have the block inspected, there may be plenty of material in all cylinders.
|
|
|
|
|
PROSTOCKTOM
Supporter of TheAMCForum 
Joined: Jun/20/2010 Location: Indiana Status: Offline Points: 2458 |
Post Options
Thanks(0)
Quote Reply
Posted: Dec/13/2018 at 5:56pm |
|
Personally I would sleeve the bad cylinder and go with it.
Having recently had a discussion with Kevin Fontenot's aka: (Stickshifter) about 401 wall thickness here's what he had to say about the matter. "The max bore on a standard iron block is 4.250 and I would never do that. The max I would do is 4.200 and even then I would check wall thickness with a sonic checker before starting. Being a virgin block makes no difference. And you need to check all cylinders in many difference location, especially around the head bolt areas near the top."  With that said, I would trust Kevin's recommendation without question. He has been there and done it and his advice could save you a lot of grief down the road. Tom |
|
|
|
|
Trader
AMC Addicted
Joined: May/15/2018 Location: Ontario Status: Offline Points: 6910 |
Post Options
Thanks(0)
Quote Reply
Posted: Dec/13/2018 at 9:03pm |
|
Posted is the 4.250" bore i.m presuming. From the numbers this block max would be 4.195" and that would be a push.
I'll be doing a 73 block this spring at 0.030" over and hope never to push this far. Some of those mid numbers are just plain scary. Distortion after torquing the head bolts would be significant to say the least. This thing survived? How long? Assuming the block was filled for race application???
|
|
|
|
|
shootist
AMC Addicted
Joined: May/24/2012 Location: Triad, NC Status: Offline Points: 1023 |
Post Options
Thanks(0)
Quote Reply
Posted: Dec/14/2018 at 12:25pm |
The original post stated #7 was the one with rust so I believe some folks assumed the damage is at a level where it needs to be bored out. Putting in a sleeve and reusing the pistons he has would be a good and cost effective option. There is a lot of assumption in that but certainly a viable approach for someone on a tighter budget. I suppose some other valid questions would be how did water get into the bore? Are you building for performance or longevity? Is budget a concern? Checking out what you have completely would be a wise move before doing anything with it. |
|
|
|
|
|
|
|
74Bubblefender
AMC Addicted
Charter Member Joined: Jun/29/2007 Location: The AMC form Status: Offline Points: 2589 |
Post Options
Thanks(0)
Quote Reply
Posted: Dec/14/2018 at 3:39pm |
|
What also affects the thickness of the cylinder walls is the coolant you use. The last 401 went in a 1979 jeep and that was 40 years ago. If the block ran a low mix of coolant and mostly water or low on coolant...letting it freeze or sit to rust the casting will shed into the coolant over time. If you ever get a chance to cut a few blocks in half you will see this. It really should be minimal...maybe .03-.04" but that be the difference between crack and no crack. Always best to sonic check the block from 1:00-4:00 and from 6:00 to 11:00 positions. 12:00 and 5:00 will never be thinner than those other areas. I should say...shouldnt ever be. Whenever possible a sleeve should not be considered.
|
|
|
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564 |
|
|
|
|
farna
Supporter of TheAMCForum
Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19689 |
Post Options
Thanks(0)
Quote Reply
Posted: Dec/15/2018 at 8:01am |
|
PROSTOCKTOM -- on the block diagram you posted there are three measurements for each position. Am I correct in assuming that the largest is the sidewall thickness of the block "as is" and the smaller measurements are the sidewall thickness of some overbore? Looks like 0.020" each time??
|
|
|
Frank Swygert
|
|
|
|
|
farna
Supporter of TheAMCForum
Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19689 |
Post Options
Thanks(0)
Quote Reply
Posted: Dec/15/2018 at 8:06am |
|
Small pits in a cylinder wall won't hurt a thing. Won't leak compression around them, not enough to be measurable anyway. I've run several engines (sixes, but doesn't really matter) that had pits where rings had rusted in the cylinders. These were stock rebuilds, but there was no difference when some of the pits were left. Compression readings were up where a stock rebuild should be. The cylinders were bored due to wear, but just bored the next common size (usually 0.030, one old 196 was bored 0.040 though). That cleaned half or more of the pits, but still left a few. Machinist didn't really like it, but the option was to get another block or sleeve three cylinders on one of them. He didn't think they would make a difference either, just didn't like seeing them... neither did I! But we went ahead and it ran like a champ for years... might still be going (sold).
|
|
|
Frank Swygert
|
|
|
|
|
Boris Badanov
AMC Addicted
Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4210 |
Post Options
Thanks(0)
Quote Reply
Posted: Dec/16/2018 at 8:01am |
|
You have to think that the machine shop that took it to .03 over
may have shifted the bores. Most shops used a simple three fingered probe to locate the bore on center. the chance of a error is rather big. That's is partly why AMC recommended no more than .02 over. Setting it up in a mill and picking up the datums, so called Blue printing is expensive. I bet most automotive machine shops today cant do it. Sleeve the bad cylinder and be done with it. Or maybe sleeve all 8 and go to 4.25 bore :-) |
|
|
Gremlin Dreams
|
|
|
|
|
Post Reply
|
Page <12 |
Tweet
|
| Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |
Click for TheAMCForum Rules
Topic Options
Trader wrote: